Vessel sealer and divider with stop members

ABSTRACT

An endoscopic bipolar forceps includes an elongated shaft having opposing jaw members at a distal end thereof. The jaw members are movable relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween. The jaws members are connected to a source of electrical energy such that the jaw members are capable of conducting energy through tissue held therebetween to effect a tissue seal. At least one non-conductive and spaced-apart stop member is disposed on an inner-facing surface of the jaw members to regulate the gap distance between the jaw members when tissue is held therebetween. The forceps also includes a longitudinally reciprocating knife which severs the tissue after sealing at a location which is proximate the sealing site.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/338,663, filed on Oct. 31, 2016, which is a continuation of U.S.application Ser. No. 14/719,887, filed on May 22, 2015, which is acontinuation of U.S. application Ser. No. 13/584,194, filed on Aug. 13,2012, which is a continuation of U.S. application Ser. No. 12/348,748,filed on Jan. 5, 2009, now U.S. Pat. No. 8,241,284, which is acontinuation of U.S. application Ser. No. 10/471,818, filed on Sep. 11,2003, now U.S. Pat. No. 7,473,253, which claims the benefit of andpriority to PCT Application Serial No. PCT/US/01/11413, filed Apr. 6,2001, entitled “VESSEL SEALER AND DIVIDER WITH NON-CONDUCTIVE STOPMEMBERS”, the entire contents of each of these applications is herebyincorporated by reference.

BACKGROUND

The present disclosure relates to an electrosurgical instrument andmethod for performing endoscopic surgical procedures. More particularly,the present disclosure relates to an endoscopic bipolar electrosurgicalforceps and method of using same which includes a non-conductive stopmember associated with one or both of the opposing jaw members. Thenon-conductive stop member is designed to control the gap distancebetween opposing jaw members and enhance the manipulation and grippingof tissue during the sealing and dividing process.

TECHNICAL FIELD

Endoscopic forceps utilize mechanical action to constrict, grasp,dissect and/or clamp tissue. Endoscopic electrosurgical forceps utilizeboth mechanical clamping action and electrical energy to effecthemostasis by heating the tissue and blood vessels to coagulate,cauterize and/or seal tissue.

Endoscopic instruments are inserted into the patient through a cannula,or port, that has been made with a trocar or similar such device.Typical sizes for cannulas range from three millimeters to twelvemillimeters. Smaller cannulas are usually preferred, and this presents adesign challenge to instrument manufacturers who must find ways to makesurgical instruments that fit through the cannulas.

Certain endoscopic surgical procedures require cutting blood vessels orvascular tissue. However, due to space limitations surgeons can havedifficulty suturing vessels or performing other traditional methods ofcontrolling bleeding, e.g., clamping and/or tying-off transected bloodvessels. Blood vessels, in the range below two millimeters in diameter,can often be closed using standard electrosurgical techniques. However,if a larger vessel is severed, it may be necessary for the surgeon toconvert the endoscopic procedure into an open-surgical procedure andthereby abandon the benefits of laparoscopy.

Several journal articles have disclosed methods for sealing small bloodvessels using electrosurgery. An article entitled Studies on Coagulationand the Development of an Automatic Computerized Bipolar Coagulator, J.Neurosurg., Volume 75, July 1991, describes a bipolar coagulator whichis used to seal small blood vessels. The article states that it is notpossible to safely coagulate arteries with a diameter larger than 2 to2.5 mm. A second article is entitled Automatically Controlled BipolarElectrocoagulation—“COA-COMP”, Neurosurg. Rev. (1984), pp. 187-190,describes a method for terminating electrosurgical power to the vesselso that charring of the vessel walls can be avoided.

As mentioned above, by utilizing an electrosurgical forceps, a surgeoncan either cauterize, coagulate/desiccate and/or simply reduce or slowbleeding, by controlling the intensity, frequency and duration of theelectrosurgical energy applied through the jaw members to the tissue.The electrode of each jaw member is charged to a different electricpotential such that when the jaw members grasp tissue, electrical energycan be selectively transferred through the tissue.

In order to effect a proper seal with larger vessels, two predominantmechanical parameters must be accurately controlled—the pressure appliedto the vessel and the gap distance between the electrodes—both of whichare affected by the thickness of the sealed vessel. More particularly,accurate application of pressure is important to oppose the walls of thevessel; to reduce the tissue impedance to a low enough value that allowsenough electrosurgical energy through the tissue; to overcome the forcesof expansion during tissue heating; and to contribute to the end tissuethickness which is an indication of a good seal. It has been determinedthat a typical fused vessel wall is optimum between 0.001 and 0.005inches. Below this range, the seal may shred or tear and above thisrange the lumens may not be properly or effectively sealed.

Electrosurgical methods may be able to seal larger vessels using anappropriate electrosurgical power curve, coupled with an instrumentcapable of applying a large closure force to the vessel walls. It isthought that the process of coagulating small vessels is fundamentallydifferent than electrosurgical vessel sealing. For the purposes herein,“coagulation” is defined as a process of desiccating tissue wherein thetissue cells are ruptured and dried. Vessel sealing is defined as theprocess of liquefying the collagen in the tissue so that it reforms intoa fused mass. Thus, coagulation of small vessels is sufficient topermanently close them. Larger vessels need to be sealed to assurepermanent closure.

U.S. Pat. No. 2,176,479 to Willis, U.S. Pat. Nos. 4,005,714 and4,031,898 to Hiltebrandt, U.S. Pat. Nos. 5,827,274, 5,290,287 and5,312,433 to Boebel et al., U.S. Pat. Nos. 4,370,980, 4,552,143,5,026,370 and 5,116,332 to Lottick, U.S. Pat. No. 5,443,463 to Stern etal., U.S. Pat. No. 5,484,436 to Eggers et al. and U.S. Pat. No.5,951,549 to Richardson et al., all relate to electrosurgicalinstruments for coagulating, cutting and/or sealing vessels or tissue.However, some of these designs may not provide uniformly reproduciblepressure to the blood vessel and may result in an ineffective ornon-uniform seal.

For the most part, these instruments rely on clamping pressure alone toprocure proper sealing thickness and are not designed to take intoaccount gap tolerances and/or parallelism and flatness requirementswhich are parameters which, if properly controlled, can assure aconsistent and effective tissue seal. For example, it is known that itis difficult to adequately control thickness of the resulting sealedtissue by controlling clamping pressure alone for either of tworeasons: 1) if too much force is applied, there is a possibility thatthe two poles will touch and energy will not be transferred through thetissue resulting in an ineffective seal; or 2) if too low a force isapplied the tissue may pre-maturely move prior to activation and sealingand/or a thicker, less reliable seal may be created.

Typically and particularly with respect to endoscopic electrosurgicalprocedures, once a vessel is sealed, the surgeon has to remove thesealing instrument from the operative site, substitute a new instrumentthrough the cannula and accurately sever the vessel along the newlyformed tissue seal. As can be appreciated, this additional step may beboth time consuming (particularly when sealing a significant number ofvessels) and may contribute to imprecise separation of the tissue alongthe sealing line due to the misalignment or misplacement of the severinginstrument along the center of the tissue sealing line.

Several attempts have been made to design an instrument whichincorporates a knife or blade member which effectively severs the tissueafter forming a tissue seal. For example, U.S. Pat. No. 5,674,220 to Foxet al. discloses a transparent vessel sealing instrument which includesa longitudinally reciprocating knife which severs the tissue oncesealed. The instrument includes a plurality of openings which enabledirect visualization of the tissue during the sealing and severingprocess. This direct visualization allows a user to visually andmanually regulate the closure force and gap distance between jaw membersto reduce and/or limit certain undesirable effects known to occur whensealing vessels, thermal spread, charring, etc. As can be appreciated,the overall success of creating a tissue seal with this instrument isgreatly reliant upon the user's expertise, vision, dexterity, andexperience in judging the appropriate closure force, gap distance andlength of reciprocation of the knife to uniformly, consistently andeffectively seal the vessel and separate the tissue at the seal.

U.S. Pat. No. 5,702,390 to Austin et al. discloses a vessel sealinginstrument which includes a triangularly-shaped electrode which isrotatable from a first position to seal tissue to a second position tocut tissue. Again, the user must rely on direct visualization andexpertise to control the various effects of sealing and cutting tissue.

Thus, a need exists to develop an endoscopic electrosurgical instrumentwhich effectively and consistently seals and separates vascular tissueand solves the aforementioned problems. This instrument regulates thegap distances between opposing jaws members, reduces the chances ofshort circuiting the opposing jaws during activation and assists inmanipulating, gripping and holding the tissue prior to and duringactivation and separation of the tissue.

SUMMARY

The present disclosure relates to an endoscopic bipolar electrosurgicalforceps for clamping, sealing and/or dividing tissue. The forcepsincludes an elongated shaft having opposing jaw members at a distal endthereof. The jaw members are movable relative to one another from afirst position wherein the jaw members are disposed in spaced relationrelative to one another to a second position wherein the jaw memberscooperate to grasp tissue therebetween. An electrosurgical energy sourceis connected to the jaw members such that the jaw members are capable ofconducting energy through tissue held therebetween to effect a tissueseal. At least one non-conductive and spaced-apart stop member isdisposed on an inner-facing surface of at least one of the jaw membersand is positioned to control the gap distance between the opposing jawmembers when the tissue is held therebetween. A longitudinallyreciprocating knife severs the tissue proximate the sealing site once aneffective seal is formed.

One embodiment of the presently disclosed forceps includes a drive rodassembly which connects the jaw members to the source of electricalenergy such that the first jaw member has a first electrical potentialand the second jaw member has a second electrical potential. Preferably,a handle mechanically engages the drive rod assembly and impartsmovement of the first and second jaw members relative to one another.

In one embodiment of the present disclosure, one of the jaw membersincludes an electrically conductive surface having alongitudinally-oriented channel defined therein which facilitateslongitudinal reciprocation of the knife for severing tissue. Preferably,the forceps includes a trigger for actuating the knife which isindependently operable from the drive assembly.

In one embodiment, the forceps includes at least two stop membersarranged as a series of longitudinally-oriented projections which extendalong the inner-facing surface from the proximal end to the distal endof the jaw member. In another embodiment, the stop members include aseries of circle-like tabs which project from the inner facing surfaceand extend from the proximal end to the distal end of the jaw member.The stop members may be disposed on either opposing jaw member onopposite sides of the longitudinally-oriented channel and/or in analternating, laterally-offset manner relative to one another along thelength of the surface of either or both jaw members.

In another embodiment of the present disclosure, a raised lip isprovided to act as a stop member which projects from the inner-facingsurface and extends about the outer periphery of the jaw member tocontrol the gap distance between opposing jaw members. In anotherembodiment, at least one longitudinally-oriented ridge extends from theproximal end to the distal end of one of the jaw members and controlsthe gap distance between the jaw members.

Preferably, the stop members are affixed/attached to the jaw member(s)by stamping, thermal spraying, overmolding and/or by an adhesive. Thestop members project from about 0.001 inches to about 0.005 inches and,preferably, from about 0.002 inches to about 0.003 inches from theinner-facing surface of at least one of the jaw members. It isenvisioned that the stop members may be made from an insulative materialsuch as parylene, nylon and/or ceramic. Other materials are alsocontemplated, e.g., syndiotactic polystryrenes such as QUESTRA®manufactured by DOW Chemical, Syndiotactic-polystryrene (SPS),Polybutylene Terephthalate (PBT), Polycarbonate (PC), AcrylonitrileButadiene Styrene (ABS), Polyphthalamide (PPA), Polymide, PolyethyleneTerephthalate (PET), Polyamideimide (PAI), Acrylic (PMMA), Polystyrene(PS and HIPS), Polyether Sulfone (PES), Aliphatic Polyketone, Acetal(POM) Copolymer, Polyurethane (PU and TPU), Nylon withPolyphenylene-oxide dispersion and Acrylonitrile Styrene Acrylate.

Another embodiment of the present disclosure includes an endoscopicbipolar forceps for sealing and dividing tissue having at least oneelongated shaft having opposing jaw members at a distal end thereof. Thejaw members are movable relative to one another from a first positionwherein the jaw members are disposed in spaced relation relative to oneanother to a second position wherein the jaw members cooperate to grasptissue therebetween. A drive rod assembly connects the jaw members to asource of electrical energy such that the first jaw member has a firstelectrical potential and the second jaw member has a second electricalpotential. The jaw members, when activated, conduct energy through thetissue held between the jaw members to effect a tissue seal. A handleattaches to the drive rod assembly and, when actuated, imparts movementof the first and second jaw members relative to one another via thedrive rod assembly. At least one non-conductive and spaced-apart stopmember is disposed on the inner facing surface of one of the jaw membersand operates to control the overall gap distance between the opposingseal surfaces of the jaw members when tissue is held therebetween. Atrigger mechanically activates a knife for severing the tissue proximatethe tissue sealing site.

The present disclosure also relates to a method for sealing and dividingtissue and includes the steps of providing an endoscopic bipolar forcepswhich includes an elongated shaft having opposing jaw members at adistal end thereof which cooperate to grasp tissue therebetween, atleast one non-conductive and spaced-apart stop member disposed on aninner facing surface of at least one of the jaw members which controlsthe distance between the jaw members when tissue is held therebetween,and a knife.

The method further includes the steps of: connecting the jaw members toa source of electrical energy; actuating the jaw members to grasp tissuebetween opposing jaw members; conducting energy to the jaw members tothrough tissue held therebetween to effect a seal; and actuating theknife to sever tissue proximate the seal.

Preferably, at least one of the jaw members of the providing stepincludes an electrically conductive surface having alongitudinally-oriented channel defined therein which facilitatesactuation of the knife in a longitudinally reciprocating fashion withinthe channel for severing the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a perspective view of an endoscopic forceps showing a handleand an end effector according to the present disclosure;

FIG. 2 is a partial cross-section of the forceps of FIG. 1 showing theinternal working components of the handle and showing the end effectorin a closed configuration;

FIG. 3 is an enlarged, perspective view of the end effector assemblyshown in open configuration;

FIG. 4 is a greatly enlarged, side view of a proximal end of the endeffector of FIG. 3;

FIG. 5 is a greatly enlarged perspective view of a distal end of the endeffector of FIG. 3 showing a knife and a series of stop members disposedalong an inner facing surface of a jaw member;

FIGS. 6A-6F show various configurations for the stop members on theinner facing surface of one of the jaw members;

FIG. 7 is an enlarged perspective view of a sealing site of a tubularvessel;

FIG. 8 is a longitudinal cross-section of the sealing site taken alongline 8-8 of FIG. 7; and

FIG. 9 is a longitudinal cross-section of the sealing site of FIG. 7after separation of the tubular vessel.

DETAILED DESCRIPTION

Referring now to FIGS. 1-5, one embodiment of an endoscopic bipolarforceps 10 is shown for use with various surgical procedures andincludes a housing and handle assembly 80 having an end effectorassembly 20 attached thereto. More particularly, forceps 10 includes ashaft 12 which has a distal end 14 dimensioned to mechanically engagewith the end effector assembly 20 and a proximal end 16 whichmechanically engages the housing and handle assembly 80. In the drawingsand in the descriptions which follow, the term “proximal”, as istraditional, will refer to the end of the forceps 10 which is closer tothe user, while the term “distal” will refer to the end which is furtherfrom the user.

The end effector assembly 20 is attached to the distal end 14 of shaft12 and includes a pair of opposing jaw members 22 and 24. Preferably,housing and handle assembly 80 is attached to the proximal end 16 ofshaft 12 and includes internally-disposed activating mechanisms, e.g., amovable handle 82 and a drive assembly 70, which mechanically cooperateto impart movement of the jaw members 22 and 24 from an open positionwherein the jaw members 22 and 24 are disposed in spaced relationrelative to one another, to a clamping or closed position wherein thejaw members 22 and 24 cooperate to grasp tissue 150 (FIG. 7)therebetween.

It is envisioned that the forceps 10 may be designed such that it isfully or partially disposable depending upon a particular purpose or toachieve a particular result. For example, end effector assembly 20 maybe selectively and releasably engageable with the distal end 14 of theshaft 12 and/or the proximal end 16 of the shaft 12 may be selectivelyand releasably engageable with the housing and handle assembly 80. Ineither of these two instances, the forceps 10 would be considered“partially disposable”, i.e., a new or different end effector assembly20 (or end effector assembly 20 and shaft 12) selectively replaces theold end effector assembly 20 as needed.

FIGS. 1 and 2 show the operating elements and the internal-workingcomponents of the housing and handle assembly 80 which for the purposesof the present disclosure are generally described herein. The specificfunctions and operative relationships of these elements and the variousinternal-working components are described in more detail in commonlyassigned, co-pending application U.S. Serial No. PCT/US01/11340,entitled “VESSEL SEALER AND DIVIDER” by Dycus et al. which is beingfiled concurrently herewith and which is hereby incorporated byreference herein in its entirety.

As best shown in FIG. 2, housing and handle assembly 80 includes movablehandle 82 and a fixed handle 84. The movable handle 82 includes anaperture 89 defined therethrough which enables a user to grasp and movethe handle 82 relative to the fixed handle 84. Movable handle 82 isselectively moveable about a pivot 87 from a first position relative tofixed handle 84 to a second position in closer proximity to the fixedhandle 84 which, as explained below, imparts relative movement of thejaw members 22 and 24 relative to one another.

More particularly, housing and handle assembly 80 houses a driveassembly 70 which cooperates with the movable handle 82 to impartmovement of the jaw members 22 and 24 from an open position wherein thejaw members 22 and 24 are disposed in spaced relation relative to oneanother, to a clamping or closed position wherein the jaw members 22 and24 cooperate to grasp tissue 150 (FIG. 7) therebetween. The generaloperating parameters of the drive assembly 70 and the internal-workingcomponents of the same are explained in a more generalized fashion belowbut are explained in specific detail in the above-mentioned commonlyassigned, co-pending “VESSEL SEALER AND DIVIDER” application. For thepurposes of the present disclosure, the housing and handle assembly 80can generally be characterized as a four-bar mechanical linkage composedof the following elements: movable handle 82, a link 73, a cam-like link76 and a base link embodied by fixed pivot points 75 and 76. Movement ofthe handle 82 activates the four-bar linkage which, in turn, actuatesthe drive assembly 70 for imparting movement of the opposing jaw members22 and 24 relative to one another to grasp tissue 150 therebetween. Itis envisioned that employing a four-bar mechanical linkage will enablethe user to gain a significant mechanical advantage when compressing thejaw members 22 and 24 against the tissue 150 as explained in furtherdetail below with respect the generally disclosed operating parametersof the drive assembly 70.

Preferably, fixed handle 84 includes a channel 85 defined therein whichis dimensioned to receive a flange 83 which extends proximally frommovable handle 82. Preferably, flange 83 includes a fixed end 90 whichis affixed to movable handle 82 and a free end 92 which is dimensionedfor facile reception within channel 85 of handle 84. It is envisionedthat flange 83 may be dimensioned to allow a user to selectively,progressively and incrementally move jaw members 22 and 24 relative toone another from the open to closed positions. For example, it is alsocontemplated that flange 83 may include a ratchet-like interface whichlockingly engages the movable handle 82 and, therefore, jaw members 22and 24 at selective, incremental positions relative to one anotherdepending upon a particular purpose. Other mechanisms may also beemployed to control and/or limit the movement of handle 82 relative tohandle 84 (and jaw members 22 and 24) such as, e.g., hydraulic,semi-hydraulic and/or gearing systems.

As can be appreciated by the present disclosure and as explained in moredetail with respect to the above-mentioned commonly assigned, co-pending“VESSEL SEALER AND DIVIDER” application, channel 85 of fixed handle 84includes an entrance pathway 91 and an exit pathway 95 for reciprocationof flange 83. As best shown in FIG. 2, as handle 82 moves in a generallypivoting fashion towards fixed handle 84 about pivot 87, link 73 rotatesabout a guide pin 74 disposed within handle 82. As a result, link 73rotates proximally about a pivot 76. As can be appreciated, the pivotingpath of handle 82 relative to fixed handle 84 biases cam-like link 76 torotate about pivot 75 in a generally proximal direction. Movement of thecam-like link 76 imparts movement to the drive assembly 70 as explainedbelow.

As best shown in FIG. 2, upon initial movement of handle 82 towardsfixed handle 84, the free end 92 of flange 83 moves generally proximallyand upwardly along entrance pathway 91 until end 92 passes ormechanically engages a rail member 97 disposed along pathway 91. It isenvisioned that rail 97 permits movement of flange 83 proximally untilthe point where end 92 clears rail 97. Once end 92 clears rail 97,distal movement of the handle 82 and flange 83, i.e., release, isredirected by rail 97 into the exit pathway 95.

More particularly, upon initial release, i.e., a reduction in theclosing pressure of handle 82 against handle 84, the handle 82 returnsslightly distally towards pathway 91 but is directed towards exitpathway 95. At this point, the release or return pressure between thehandles 82 and 84 which is attributable and directly proportional to therelease pressure associated with the compression of the drive assembly70 (explained below) causes the end 92 of flange 83 to settle or lockwithin a catch basin 93. Handle 82 is now secured in position withinhandle 84 which, in turn, locks the jaw members 22 and 24 in a closedposition against the tissue. The instrument is now positioned forselective application of electrosurgical energy to form the tissue seal152. Again, the various operating elements and their relevant functionsare explained in more detail with respect to the above-mentionedcommonly assigned, co-pending “VESSEL SEALER AND DIVIDER” application.

As best shown in FIG. 2, re-initiation or re-grasping of the handle 82again moves flange 83 generally proximally along the newly re-directedexit path 95 until end 92 clears a lip 94 disposed along exit pathway95. Once lip 94 is sufficiently cleared, handle 82 and flange 83 arefully and freely releasable from handle 84 along exit pathway 95 uponthe reduction of grasping pressure which, in turn, returns the jawmembers 22 and 24 to the open, pre-activated position.

As mentioned above, the housing and handle assembly 80 houses a driveassembly 70 which cooperates with the movable handle 82 to impartrelative movement of the jaw members 22 and 24 to grasp the tissue 150.The operation of the drive rod assembly 70 and the various workingcomponents of the drive assembly 70 are explained in detail in theabove-mentioned commonly assigned, co-pending “VESSEL SEALER ANDDIVIDER” application.

Generally and for the purposes of the present disclosure, the driveassembly 70 includes a compression spring 72, a drive rod 40 and acompression sleeve 98 (FIG. 2). As best shown in the enlarged view ofFIG. 4, the drive rod 40 is telescopically and internally reciprocablewithin a knife sleeve 48. Movement of the drive rod 40 relative to theknife sleeve 48 imparts movement to the jaw members 22 and 24. A tabmember 46 is disposed at a free end 42 of the drive rod 40 which definesa notch 43 between the tab 46 and end 42. The tab 46 and the notch 43mechanically cooperate with the compression spring 72 to impart movementof the shaft 40 relative to the knife sleeve 48 which, in turn, opensand closes the jaw members 22 and 24 about the tissue 150.

As explained above, movement of the handle assembly 80 via the four-barlinkage, ultimately causes cam-like link 76 to rotate generallyclockwise about pivot 75 (i.e. proximally) which, in turn, compressesspring 72 proximally against a flange 77 disposed within the upperportion of the fixed handle 84. Movement of the spring 72, in turn,moves the drive rod 40 relative to the knife sleeve 48 which moves theopposing jaw members 22 and 24 relative to one another. As can beappreciated, the significant mechanical advantage associated with thefour-bar linkage permits facile, consistent and uniform compression ofthe spring 72 which, in turn, permits facile, consistent and uniformcompression of the jaw members 22 and 24 about the tissue 150. Otherdetails and advantages of the four-bar mechanical linkage are more fullydiscussed with respect to the above-mentioned commonly assigned,co-pending “VESSEL SEALER AND DIVIDER” application.

Once the tissue 150 is grasped between opposing jaw members 22 and 24,electrosurgical energy can be supplied to the jaw members 22 and 24through an electrosurgical interface 110 disposed within the handle 84.Again these features are explained in more detail with respect to theabove-mentioned commonly assigned, co-pending “VESSEL SEALER ANDDIVIDER” application.

Forceps 10 also includes a trigger 86 which reciprocates the knifesleeve 48 which, in turn, reciprocates a knife 60 disposed within theend effector assembly 20 as explained below (FIG. 5). Once the a tissueseal 152 is formed (FIG. 7), the user can activate the trigger 86 toseparate the tissue 150 as shown in FIG. 9 along the tissue seal 152. Ascan be appreciated, the reciprocating knife 60 allows the user toquickly separate the tissue 150 immediately after sealing withoutsubstituting a cutting instrument through the cannula or trocar port(not shown). It is envisioned that the knife 60 also facilitates a moreaccurate separation of the vessel 150 along an ideal cutting plane “B-B”associated with the newly formed tissue seal 152 (See FIGS. 7-9). Knife60 preferably includes a sharpened edge 62 for severing the tissue 150held between the jaw members 22 and 24 at the tissue sealing site 152(FIG. 7). It is envisioned that knife 60 may also be coupled to theelectrosurgical energy source to facilitate separation of the tissue 150along the tissue seal 152.

Preferably and as explained in more detail with respect to theabove-mentioned commonly assigned, co-pending “VESSEL SEALER ANDDIVIDER” application, handle assembly 80 may also include a lockoutmechanism (not shown) which restricts activation of trigger 86 until thejaw members 22 and 24 are closed and/or substantially closed abouttissue 150. For example and as best seen in FIG. 2, exit pathway 95 maybe dimensioned such that the trigger 86 is only activatable when flange83 is disposed in a predetermined or predefined position which providessufficient clearance for the activation of the trigger 86, e.g., seatedwithin catch basin 93. It is envisioned that configuring the handleassembly 80 in this fashion may reduce the chances of prematureactivation of the trigger 86 prior to electrosurgical activation andsealing.

A rotating assembly 88 may also be incorporated with forceps 10.Preferably, rotating assembly 88 is mechanically associated with theshaft 12 and the drive assembly 70. As seen best in FIG. 4, the shaft 12includes an aperture 44 located therein which mechanically interfaces acorresponding detent (not shown) affixed to rotating assembly 88 suchthat rotational movement of the rotating assembly 88 imparts similarrotational movement to the shaft 12 which, in turn, rotates the endeffector assembly 20 about a longitudinal axis “A”. These features alongwith the unique electrical configuration for the transference ofelectrosurgical energy through the handle assembly 80, the rotatingassembly 88 and the drive assembly 70 are described in more detail inthe above-mentioned commonly assigned, co-pending “VESSEL SEALER ANDDIVIDER” application.

As best seen with respect to FIGS. 3, 5 and 6A-6F, end effector assembly20 attaches to the distal end 14 of shaft 12. The end effector assembly20 includes the first jaw member 22, the second jaw member 24 and thereciprocating knife 60 disposed therebetween. The jaw members 22 and 24are preferably pivotable about a pivot 37 from the open to closedpositions upon relative reciprocation, i.e., longitudinal movement, ofthe drive rod 42 as mentioned above. Again, the mechanical andcooperative relationships with respect to the various moving elements ofthe end effector assembly 20 are further described with respect to theabove-mentioned commonly assigned, co-pending “VESSEL SEALER ANDDIVIDER” application.

Each of the jaw members includes an electrically conductive sealingsurface 35 dispose on inner-facing surface 34 thereof and an insulator30 disposed on an outer-facing surface 39 thereof. It is envisioned thatthe electrically conductive surfaces 35 cooperate to seal tissue 150held therebetween upon the application of electrosurgical energy. Theinsulators 30 together with the outer, non-conductive surfaces 39 of thejaw members 22 and 24 are preferably dimensioned to limit and/or reducemany of the known undesirable effects related to tissue sealing, e.g.,flashover, thermal spread and stray current dissipation.

It is envisioned that the electrically conductive sealing surfaces 35may also include a pinch trim which facilitates secure engagement of theelectrically conductive surface 35 to the insulator 30 and alsosimplifies the overall manufacturing process. It is envisioned that theelectrically conductive sealing surface 35 may also include an outerperipheral edge which has a radius and the insulator 30 meets theelectrically conductive sealing surface 35 along an adjoining edge whichis generally tangential to the radius and/or meets along the radius.Preferably, at the interface, the electrically conductive surface 35 israised relative to the insulator 30. These and other envisionedembodiments are discussed in concurrently-filed, co-pending, commonlyassigned Application Serial No. PCT/US01/11412 entitled “ELECTROSURGICALINSTRUMENT WHICH REDUCES COLLATERAL DAMAGE TO ADJACENT TISSUE” byJohnson et al. and concurrently-filed, co-pending, commonly assignedApplication Serial No. PCT/US01/11411 entitled “ELECTROSURGICALINSTRUMENT WHICH IS DESIGNED TO REDUCE THE INCIDENCE OF FLASHOVER” byJohnson et al. The entire contents of both of these applications arehereby incorporated by reference herein.

Preferably, a least one of the electrically conductive surfaces 35 ofthe jaw members, e.g., 22, includes a longitudinally-oriented channel 36defined therein which extends from a proximal end 26 to a distal end 28of the jaw member 22. It is envisioned that the channel 36 facilitateslongitudinal reciprocation of the knife 60 along a preferred cuttingplane “B-B” to effectively and accurately separate the tissue 150 alongthe formed tissue seal 152 (See FIGS. 7-9). Preferably and as explainedin detail in the above-mentioned commonly assigned, co-pending “VESSELSEALER AND DIVIDER” application, the jaw members 22 and 24 of the endeffector assembly 22 are electrically isolated from one another suchthat electrosurgical energy can be effectively transferred through thetissue 150 to form seal 152.

As mentioned above, upon movement of the handle 82, the jaw members 22and 24 close together and grasp tissue 150. At this point flange 83becomes seated within catch 93 which, together with the mechanicaladvantage associated with the four-bar mechanism and the spring 70,maintains a proportional axial force on the drive rod 40 which, in turn,maintains a compressive force between opposing jaw members 22 and 24against the tissue 150. It is envisioned that the end effector assembly20 may be dimensioned to off-load excessive clamping forces to preventmechanical failure of certain internal operating elements of the endeffector.

By controlling the intensity, frequency and duration of theelectrosurgical energy applied to the tissue 150, the user can eithercauterize, coagulate/desiccate seal and/or simply reduce or slowbleeding. As mentioned above, two mechanical factors play an importantrole in determining the resulting thickness of the sealed tissue andeffectiveness of the seal, i.e., the pressure applied between opposingjaw members 22 and 24 and the gap distance between the opposing sealingsurfaces 35 of the jaw members 22 and 24 during the sealing process.However, thickness of the resulting tissue seal 152 cannot be adequatelycontrolled by force alone. In other words, too much force and the twojaw members 22 and 24 would touch and possibly short resulting in littleenergy traveling through the tissue 150 thus resulting in a bad tissueseal 152. Too little force and the seal 152 would be too thick.

Applying the correct force is also important for other reasons: tooppose the walls of the vessel; to reduce the tissue impedance to a lowenough value that allows enough current through the tissue 150; and toovercome the forces of expansion during tissue heating in addition tocontributing towards creating the required end tissue thickness which isan indication of a good seal.

Preferably, the electrically conductive sealing surfaces 35 of the jawmembers 22 and 24 are relatively flat to avoid current concentrations atsharp edges and to avoid arcing between high points. In addition and dueto the reaction force of the tissue 150 when engaged, jaw members 22 and24 are preferably manufactured to resist bending. For example and asbest seen in FIG. 6A, the jaw members 22 and 24 are preferably taperedalong width “W” which is advantageous for two reasons: 1) the taper willapply constant pressure for a constant tissue thickness at parallel; 2)the thicker proximal portion of the jaw members 22 and 24 will resistbending due to the reaction force of the tissue 150.

As best seen in FIGS. 5-6F, in order to achieve a desired spacingbetween the electrically conductive surfaces 35 of the respective jawmembers 22 and 24, (i.e., gap distance) and apply a desired force toseal the tissue 150, at least one jaw member 22 and/or 24 includes atleast one stop member, e.g., 50 a, which limits the movement of the twoopposing jaw members 22 and 24 relative to one another. Preferably, thestop member, e.g., 50 a, extends from the sealing surface or tissuecontacting surface 35 a predetermined distance according to the specificmaterial properties (e.g., compressive strength, thermal expansion,etc.) to yield a consistent and accurate gap distance during sealing.Preferably, the gap distance between opposing sealing surfaces 35 duringsealing ranges from about 0.001 inches to about 0.005 inches and, morepreferably, between about 0.002 and about 0.003 inches.

Preferably, stop members 50 a-50 g are made from an insulative material,e.g., parylene, nylon and/or ceramic and are dimensioned to limitopposing movement of the jaw members 22 and 24 to within the abovementioned gap range. It is envisioned that the stop members 50 a-50 gmay be disposed on one or both of the jaw members 22 and 24 dependingupon a particular purpose or to achieve a particular result.

FIGS. 6A-6F show various contemplated configurations of thenon-conductive stop members 50 a-50 g disposed on, along or protrudingthrough the jaw member 24. It is envisioned that one or more stopmembers, e.g., 50 a and 50 g, can be positioned on either or both jawmembers 22 and 24 depending upon a particular purpose or to achieve adesired result. As can be appreciated by the present disclosure, thevarious configurations of the stop members 50 a-50 g are designed toboth limit the movement of the tissue 150 prior to and during activationand prevent short circuiting of the jaw members 22 and 24 as the tissue150 is being compressed.

FIGS. 6A and 6B show one possible configuration of the stop members 50a-50 g for controlling the gap distance between opposing seal surfaces35. More particularly, a pair of longitudinally-oriented tab-like stopmembers 50 a are disposed proximate the center of sealing surface 35 onone side of the knife channel 36 of jaw member 24. A second stop member,e.g., 50 b, is disposed at the proximal end 26 of jaw member 24 and athird stop member 50 g is disposed at the distal tip 28 of jaw member24. Preferably, the stop members 50 a-50 g may be configured in anyknown geometric or polynomial configuration, e.g., triangular,rectilinear, circular, ovoid, scalloped, etc., depending upon aparticular purpose. Moreover, it is contemplated that any combination ofdifferent stop members 50 a-50 g may be assembled along the sealingsurfaces 35 to achieve a desired gap distance. It is also envisionedthat the stop members may be designed as a raised lip (not shown) whichprojects from the outer periphery of the jaw member 24.

FIG. 6C shows a first series of circle-like stop members 50 c extendingfrom the proximal end 26 to the distal end 28 of jaw member 24 in analternating, laterally-offset manner relative to one another on one sideof the knife channel 36 and a second series of circle-like stop members50 c extending from the proximal end 26 to the distal end 28 of jawmember 24 in an alternating, laterally-offset manner relative to oneanother on the other side of the knife channel 36. It is envisioned thatcircle-like stop members 50 c are substantially equal in size, however,one or more of the stop members 50 c may be dimensioned larger orsmaller than the other stop members 50 c depending upon a particularpurpose or to achieve a desired result.

FIG. 6D shows yet another configuration wherein the stop member isconfigured as a longitudinally-oriented ridge 50 e extending from aproximal end 26 to a distal end 28 of jaw member 82 along one side ofknife channel 36. As mentioned above, a second longitudinally-orientedridge 50 e may be disposed on opposing jaw member 22 on the oppositeside of knife channel 36 for sealing purposes. FIG. 6E shows a series ofelongated tab-like members 50 f which are disposed at an angle relativeto knife channel 36. FIG. 6F shows yet another configuration whereindifferent stop members, e.g., 50 a, 50 c and 50 g are disposed atopsealing surface 35 on both sides of the knife channel 36.

Preferably, the non-conductive stop members 50 a-50 g are molded ontothe jaw members 22 and 24 (e.g., overmolding, injection molding, etc.),stamped onto the jaw members 22 and 24 or deposited (e.g., deposition)onto the jaw members 22 and 24. The stop members 50 a-50 g may also beslideably attached to the jaw members and/or attached to theelectrically conductive surfaces 35 in a snap-fit manner. Othertechniques involve thermally spraying a ceramic material onto thesurface of the jaw member 22 and 24 to form the stop members 50 a-50 g.Several thermal spraying techniques are contemplated which involvedepositing a broad range of heat resistant and insulative materials onthe electrically conductive surfaces 35 to create stop members 50 a-50g, e.g., High velocity Oxy-fuel deposition, plasma deposition, etc.

It is envisioned that the stop members 50 a-50 g protrude about 0.001 toabout 0.005 inches from the inner-facing surfaces 35 of the jaw members22 and 24 which, as can be appreciated by the present disclosure, bothreduces the possibility of short circuiting between electricallyconductive surfaces and enhances the gripping characteristics of the jawmembers 22 and 24 during sealing and dividing. Preferably, the stopmembers 50 a-50 g protrude about 0.002 inches to about 0.003 inches fromthe electrically conductive surface 35 which has been determined yieldan ideal gap distance for producing effective, uniform and consistenttissue seals.

Alternatively, the stop members 50 a-50 g can be molded onto theinner-facing surface 35 of one or both jaw members 22 and 24 or, in somecases, it may be preferable to adhere the stop member 50 a-50 g to theinner facing surfaces 35 of one or both of the jaw members 22 and 24 byany known method of adhesion. Stamping is defined herein to encompassvirtually any press operation known in the trade, including but notlimited to: blanking, shearing, hot or cold forming, drawing, bending,and coining.

FIGS. 6A-6F show some of the possible configurations of the stop members50 a-50 f, however, these configurations are shown by way of example andshould not be construed as limiting. Other stop member configurationsare also contemplated which may be may be equally effective in reducingthe possibility of short circuiting between electrically conductivesurfaces 35 and enhancing tissue grip during sealing and dividing.

Further, although it is preferable that the stop members 50 a-50 gprotrude about 0.001 inches to about 0.005 and preferably about 0.002inches to about 0.003 inches from the inner-facing surfaces 35 of thejaw member 22 and 24, in some cases it may be preferable to have thestop members 50 a-50 g protrude more or less depending upon a particularpurpose. For example, it is contemplated that the type of material usedfor the stop members 50 a-50 g and that material's ability to absorb thelarge compressive closure forces between jaw members 22 and 24 will varyand, therefore, the overall dimensions of the stop members 50 a-50 g mayvary as well to produce the desired gap distance.

In other words, the compressive strength of the material along with thedesired or ultimate gap distance required for effective sealing areparameters which are carefully considered when forming the stop members50 a-50 g and one material may have to be dimensioned differently fromanother material to achieve the same gap distance or desired result. Forexample, the compressive strength of nylon is different from ceramicand, therefore, the nylon material may have to be dimensioneddifferently, e.g., thicker, to counteract the closing force of theopposing jaw members 22 and 24 and to achieve the same desired gapdistance when utilizing a ceramic stop member.

The present disclosure also relates to a method of sealing and dividingtissue and includes the steps of providing an endoscopic bipolar forceps10 which includes an elongated shaft 12 having opposing jaw members 22and 24 at a distal end 14 thereof which cooperate to grasp tissue 150therebetween, at least one non-conductive and spaced-apart stop member50 a-50 g disposed on an inner facing surface 35 of at least one of thejaw members, e.g., 24, which controls the distance between the jawmembers 22 and 24 when tissue 150 is held therebetween, and a knife 60.

The method further includes the steps of: connecting the jaw members 22and 24 to a source 110 of electrical energy; actuating the jaw members22 and 24 to grasp tissue 150 between opposing jaw members 22 and 24;conducting energy to the jaw members 22 and 24 to through tissue 150held therebetween to effect a seal 152 (FIGS. 7-9); and actuating theknife 60 to sever tissue proximate the seal 152.

Preferably, at least one of the jaw members, e.g., 24, of the providingstep includes an electrically conductive surface 35 having alongitudinally-oriented channel 36 defined therein which facilitatesactuation of the knife 60 in a longitudinally reciprocating fashionwithin the channel 36 for severing the tissue 150 proximate the tissuesite.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the present disclosure. For example, it may be preferable to addother features to the forceps 10, e.g., an articulating assembly toaxially displace the end effector assembly 20 relative to the elongatedshaft 12.

Moreover, it is contemplated that the presently disclosed forceps mayinclude a disposable end effector assembly which is selectivelyengageable with at least one portion of the electrosurgical instrument,e.g., shaft 12 and/or handle assembly 80.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of a preferred embodiments. Those skilled in the artwill envision other modifications within the scope and spirit of theclaims appended hereto.

What is claimed is:
 1. A bipolar electrosurgical instrument, comprising: a housing; an elongated shaft extending from the housing; opposing first and second jaw members disposed at a distal end of the elongated shaft, at least one of the first or second jaw members movable relative to the other from a first position wherein the first and second jaw members are disposed in spaced relation relative to one another to a second position wherein the first and second jaw members are closer to one another, the first and second jaw members including first and second seal surfaces, respectively, extending along a respective length thereof and adaptable to connect to a source of electrical energy such that the first and second seal surfaces are capable of conducting energy through tissue held therebetween; the first seal surface including a knife channel defined therein and extending along a portion of a length thereof; a plurality of pairs of first stop members spaced-apart along at least a portion of the length of the first seal surface, each pair of first stop members including one stop member disposed on one side of the knife channel and another stop member disposed on another side of the knife channel; a second stop member extending from the first seal surface and disposed distally of the knife channel and in longitudinal alignment therewith, wherein the first stop members protrude a first distance above the first seal surface and the second stop member protrudes a second distance above the first seal surface that is greater than the first distance; and a knife configured to translate through the knife channel.
 2. The bipolar electrosurgical instrument according to claim 1, wherein the first stop members are made from a non-conductive material.
 3. The bipolar electrosurgical instrument according to claim 1, wherein the first stop members are formed from a first material and wherein the second stop member is formed from a second material that is different from the first material.
 4. The bipolar electrosurgical instrument according to claim 1, wherein the first stop members define a first compressibility and wherein the second stop member defines a second compressibility that is different from the first compressibility.
 5. The bipolar electrosurgical instrument according to claim 1, wherein at least the plurality of pairs of first stop members are configured to enhance manipulation and gripping of tissue held between the first and second seal surfaces.
 6. The bipolar electrosurgical instrument according to claim 1, wherein at least the second stop member is configured to prevent short circuiting of the first and second seal surfaces.
 7. The bipolar electrosurgical instrument according to claim 1, wherein at least the second stop member is configured to maintain space between the first and second seal surfaces in the second position of the first and second jaw members.
 8. The bipolar electrosurgical instrument according to claim 1, wherein the second seal surfaces includes a knife channel defined therein and extending along a length thereof, the knife channels of the first and second seal surfaces configured to align with one another in the second position of the first and second jaw members to permit translation of the knife therethrough.
 9. The bipolar electrosurugical instrument according to claim 1, wherein the first stop members define a first diameter and wherein the second stop member defines a second diameter different from the first diameter.
 10. The bipolar electrosurgical instrument according to claim 1, wherein the plurality of first stop members are configured to maintain space between the first and second seal surfaces in the second position of the first and second jaw members.
 11. The bipolar electrosurgical instrument according to claim 1, wherein the second stop member is configured to contact the second seal surface without the plurality of first stop members contacting the second seal surface.
 12. A bipolar electrosurgical instrument, comprising: a housing; an elongated shaft extending from the housing; opposing first and second jaw members disposed at a distal end of the elongated shaft, at least one of the first or second jaw members movable relative to the other from a first position wherein the first and second jaw members are disposed in spaced relation relative to one another to a second position wherein the first and second jaw members are closer to one another, the first and second jaw members including first and second seal surfaces, respectively, extending along a respective length thereof and adaptable to connect to a source of electrical energy such that the first and second seal surfaces are capable of conducting energy through tissue held therebetween; the first seal surface including a knife channel defined therein and extending along a portion of a length thereof; a plurality of pairs of first stop members spaced-apart along at least a portion of the length of the first seal surface, each pair of first stop members including one stop member disposed on one side of the knife channel and another stop member disposed on another side of the knife channel; a second stop member extending above the first seal surface, the second stop member distally-spaced from a distal end of the knife channel, proximally-spaced from a distal end of the first seal surface, and disposed in longitudinal alignment with the distal end of the knife channel, wherein the second stop member is different from each of the first stop members; a knife configured to translate through the knife channel.
 13. The bipolar electrosurgical instrument according to claim 12, wherein the first stop members protrude a first distance above the first seal surface and the second stop member protrudes a second distance above the first seal surface that is greater than the first distance.
 14. The bipolar electrosurgical instrument according to claim 12, wherein the first stop members are formed from a first material and wherein the second stop member is formed from a second material that is different from the first material.
 15. The bipolar electrosurgical instrument according to claim 12, wherein the first stop members define a first compressibility and wherein the second stop member defines a second compressibility that is different from the first compressibility.
 16. The bipolar electrosurgical instrument according to claim 12, wherein at least the plurality of pairs of first stop members are configured to enhance manipulation and gripping of tissue held between the first and second seal surfaces.
 17. The bipolar electrosurgical instrument according to claim 12, wherein at least the second stop member is configured to prevent short circuiting of the first and second seal surfaces.
 18. The bipolar electrosurgical instrument according to claim 12, wherein at least the second stop member is configured to maintain space between the first and second seal surfaces in the second position of the first and second jaw members.
 19. The bipolar electrosurugical instrument according to claim 12, wherein the first stop members define a first diameter and wherein the second stop member defines a second diameter different from the first diameter.
 20. The bipolar electrosurgical instrument according to claim 12, wherein the plurality of first stop members are configured to maintain space between the first and second seal surfaces in the second position of the first and second jaw members.
 21. The bipolar electrosurgical instrument according to claim 12, wherein the second stop member is configured to contact the second seal surface without the plurality of first stop members contacting the second seal surface.
 22. A bipolar electrosurgical instrument, comprising: a housing; an elongated shaft extending from the housing; opposing first and second jaw members disposed at a distal end of the elongated shaft, at least one of the first or second jaw members movable relative to the other from a first position wherein the first and second jaw members are disposed in spaced relation relative to one another to a second position wherein the first and second jaw members are closer to one another, the first and second jaw members including first and second seal surfaces, respectively, extending along a respective length thereof and adaptable to connect to a source of electrical energy such that the first and second seal surfaces are capable of conducting energy through tissue held therebetween; the first seal surface including a knife channel defined therein and extending along a portion of a length thereof to a closed distal end, the knife channel defining a longitudinal axis; a plurality of first stop members spaced-apart along at least a portion of the length of the first seal surface, at least one of the first stop members disposed on one side of the knife channel and at least one of the first stop members disposed on another side of the knife channel; a second stop member extending above the first seal surface, the second stop member spaced-apart from a distal end of the first seal surface and the closed distal end of the knife channel in alignment on the longitudinal axis of the knife channel, wherein the second stop member is different from each of the first stop members; a knife configured to translate through the knife channel.
 23. The bipolar electrosurgical instrument according to claim 22, wherein one of the first stop members disposed on the one side of the knife channel and one of the first stop members disposed on the another side of the knife channel are arranged such that a line segment extending therebetween is disposed in perpendicular orientation relative to the longitudinal axis of the knife channel.
 24. The bipolar electrosurgical instrument according to claim 22, wherein the plurality of first stop members define a first shape and wherein the second stop member defines a second shape different from the first shape.
 25. The bipolar electrosurgical instrument according to claim 24, wherein the first shape is an elongated tab and the second shape is a circle-like tab.
 26. The bipolar electrosurgical instrument according to claim 22, wherein the plurality of first stop members and the second stop member are each formed from a non-conductive material. 